1. Field of the Invention
The present invention relates to silicone microparticles comprising silicone elastomer spherical microparticles coated with a polyorganosilsesquioxane which are able to absorb at least one of sebum and the hydrocarbon oils and ester oils that together constitute liquid oils, and also relates to a method of producing such silicone microparticles.
2. Description of the Prior Art
Following application to the skin, cosmetic make-up materials tend to gradually change their cosmetic properties over time as a result of the sebum secreted from the skin. In other words, the cosmetic material tends to lose its adhesion to the area of skin to which it has been applied as a result of the sebum, and becomes more readily transferable to other areas of the skin or clothing upon contact with such other areas of the skin or clothing. Further, sebum tends to change the color of the cosmetic material, and also causes an increase in the shine of the cosmetic material. Accordingly, cosmetic make-up materials containing sebum-absorbing powders have been proposed (for example, see Patent Document 1). However, the sebum tends to remain adsorbed to the surface of these powders, or to become absorbed in the spaces between powder particles, and because the sebum is not absorbed into the interior of the powder particles, the amount of sebum absorbed by the powder is minimal, meaning the effect of the powder in preventing discoloration or shininess of the cosmetic material is inadequate.
On the other hand, cosmetic materials containing an added liquid oil such as a paraffin or an ester are used to impart softness and smoothness to the skin, thus providing an emollient effect, but these types of cosmetic materials suffer from the unavoidable drawbacks of greasiness, stickiness, and an oily film feeling.
Conventionally, silicone particles have been used to impart cosmetic materials with favorable feelings during use, such as a feeling of silkiness or smoothness, and also to impart improved extensibility. In particular, silicone microparticles comprising spherical microparticles of a silicone rubber coated with a polyorganosilsesquioxane (see Patent Document 2) have a soft feel, are non-cohesive, and exhibit excellent dispersibility, and are therefore used in a wide variety of cosmetic materials. However, the coated silicone microparticles disclosed specifically in Patent Document 2 comprise a core of a silicone rubber spherical microparticle formed from a cured product of a silicone that comprises only lower alkyl groups as the organic groups bonded to the silicon atoms, and no mention is made of silicone microparticles capable of absorbing a large amount of at least one of sebum and liquid oils.
[Patent Document 1] WO 97/04737
[Patent Document 2] U.S. Pat. No. 5,538,793